title: Adaptation of marine plankton to environmental stress by glycolipid accumulation.
abstract: A systematic investigation of non-phosphorus containing glycolipids (GL) was conducted in the northern Adriatic Sea during two years at two stations with different nutrient loads. GL concentration varied both spatially and temporally, with values of 1.1-21.5 μg/L and 0.4-44.7 μg/L in the particulate and the dissolved fraction, respectively. The highest concentrations were measured during summer in surface waters and at the more oligotrophic station, where GL yields (% of total lipids) were often higher than 20% and 50% in the particulate and dissolved fractions, respectively. To obtain more insight into factors governing GL accumulation autotrophic plankton community structure (pico-, nano- and microplankton fractions), chlorophyll a, heterotrophic bacteria and nutrient concentrations were measured together with hydrographic parameters and sunlight intensity. During the investigated period smaller autotrophic plankton cells (pico- and followed by nanoplankton) prevailed in abundance over larger cells (microplankton), which were found in large numbers in freshened surface samples. Several major findings resulted from the study. Firstly, during PO4 limitation, particularly at the oligotrophic station, enhanced glycolipid instead of phospholipid accumulation takes place, representing an effective phosphate-conserving mechanism. Secondly, results suggest that at seawater temperatures >19 °C autotrophic plankton considerably accumulate GL, probably to achieve thermal stability. Thirdly, high sunlight intensities seem to influence increased GL accumulation; GL possibly plays a role in cell mechanisms that prevent/mitigate photooxidation. And finally, substantial accumulation of GL detected in the dissolved fraction could be related to the fact that GL do not contain biologically relevant elements, like phosphorus, which makes them an unattractive substrate for enzyme activity. Therefore, substantial portion of CO2 could be removed from the atmosphere in P-limited regions during summer via its capture by plankton and conversion to GL.
authors.affiliation: Division for Marine and Environmental Research, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia. Electronic address: gaspar@irb.hr.
authors.forename: Blaženka
authors.initials: B
authors.lastname: Gašparović
authors.forename: Jelena
authors.initials: J
authors.lastname: Godrijan
authors.forename: Sanja
authors.initials: S
authors.lastname: Frka
authors.forename: Igor
authors.initials: I
authors.lastname: Tomažić
authors.forename: Abra
authors.initials: A
authors.lastname: Penezić
authors.forename: Daniela
authors.initials: D
authors.lastname: Marić
authors.forename: Tamara
authors.initials: T
authors.lastname: Djakovac
authors.forename: Ingrid
authors.initials: I
authors.lastname: Ivančić
authors.forename: Paolo
authors.initials: P
authors.lastname: Paliaga
authors.forename: Daniel
authors.initials: D
authors.lastname: Lyons
authors.forename: Robert
authors.initials: R
authors.lastname: Precali
authors.forename: Nataša
authors.initials: N
authors.lastname: Tepić
mesh_terms: D000222:Adaptation, Physiological; D001419:Bacteria; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D006017:Glycolipids / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010933:Plankton / Q000502:physiology*; D012621:Seasons; D012623:Seawater; D013312:Stress, Physiological; D013472:Sunlight; D013696:Temperature
chemical_list: D006017:Glycolipids; D010710:Phosphates; D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: Glycolipids; Microplankton; Nanoplankton; PO(4) limitation; Picoplankton; Sunlight; Temperature